The Oldest Valentine?

Source: http://britishlibrary.typepad.co.uk/.a/6a00d8341c464853ef0147e24c9aaa970b-piIs this letter from Margery Brews to John Paston (dated February 1477) the earliest example of a Valentine? Read the story on the British Library “Medieval and Earlier Manuscripts Blog”: The Oldest Valentine? - Medieval and Earlier Manuscripts.